This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This study is a two-group, multicenter, randomized, double-masked, placebo-controlled Phase II clinical trial. All groups will receive standard intensive diabetes treatment with insulin and dietary management. 108 subjects will be randomly assigned in a 2:1 ratio to receive either two years of CTLA-rug infusions or placebo infusions. The objective of the study is to assess the safety and efficacy and mode of action of CTLA-Ig infusions for the treatment of individuals with new onset type 1 diabetes. Evaluation will be done to determine if subjects will be able to produce endogenous insulin with the treatment of CTLA-Ig.